for ( ; ;)

[Abder-Rahman Ali]

When we write the for-loop header as follows, what does it mean?

for(; ;)
{

}


Thanks

[edited to disable smilies]
[ May 22, 2008: Message edited by: Jeanne Boyarsky ]

[Jeanne Boyarsky]

Abder,
That loop runs forever since there is no end loop condition.

Normally, it looks like this:

for (int i = 0; i < 10; i++) {
  // do stuff
}

The first piece initializes, the second piece checks if we are done and the third piece moves us closer to the end.

[Abder-Rahman Ali]

Thank you very much.
[ May 22, 2008: Message edited by: Abder-Rahman Ali ]

[Rob Spoor]

A bit more elaborate:

A for loop header has three parts: the initializer, the condition and the increment. The loop will first execute the initializer part, and then while the condition returns true it will execute the loop body, then the increment.

In this example there is no initializer, no increment and no condition. If omitted, the condition yields true, so the loop is a synonym for the following:

while (true)
{
}

[Vikas Kapoor]

Originally posted by Rob Prime:
A bit more elaborate:

A for loop header has three parts: the initializer, the condition and the increment. ...

Not Always

Jeanne Boyarsky :
The first piece initializes, the second piece checks if we are done and the third piece moves us closer to the end.

[ May 23, 2008: Message edited by: Vishal Pandya ]

[Rob Spoor]

But it is still mostly called the increment statement. Wikipedia calls it the "counting expression".
You're right that it doesn't have to be an increment on integers, or even needs to be present.

[Ernest Friedman-Hill]

Originally posted by Rob Prime:
But it is still mostly called the increment statement. Wikipedia calls it the "counting expression".
You're right that it doesn't have to be an increment on integers, or even needs to be present.

The Java Language Spec calls it the "ForUpdate" part, which isn't even a word (14.14.1)! I agree -- I think most people call it the "increment."

[Jeanne Boyarsky]

I agree too. I've heard it called the increment. I choose my words more carefully so as not to imply it couldn't go backwards.

[Henry Wong]

I still remember it from when I was programming in C -- the three components of the "for" loop, in C, were the initializer, condition, and reinitializer.

Henry

[Ernest Friedman-Hill]

Both Guy Steele and K&R call them "expression1", "expression2" and "expression3" !

[Rob Spoor]

Well that certainly is self-explanatory.